Pumping nd:yvo4 and KTP with sunlight.

GooeyGus said:

sweeeeet. Looks good. What about on the other end where I'm actually collecting the sunlight? Can I just focus the lens over the ends of the fiber lines? Also, how much loss is associated with the fiber optic line? For example, If I wanted the 'sun end' of the line outside, but the actual laser inside, am I going to lose a bunch of pump power in the lines? And where can I get some decent fiber optic line? Thanks again  

Click to expand...

You could use a standard type fiber coupler. They generally have some kind of focusing lens that targets the end of the fiber. Use a large convex or fresnel to focus onto the coupler. You would need one for each fiber. With good focusing you could get as high as 70% efficiency maybe even more with the larger multimode fiber.

I haven't done the calculations but you might want to figure out if something like 2.5W/m^2 * Efficiency % * fiber count is enough pump energy. YAG is about the easiest solid state gain media to get lasing so if anything will lase with sunlight, YAG will.

FrothyChimp said:

[quote author=GooeyGus link=1218357420/0#14 date=1218489742]sweeeeet. Looks good. What about on the other end where I'm actually collecting the sunlight? Can I just focus the lens over the ends of the fiber lines? Also, how much loss is associated with the fiber optic line? For example, If I wanted the 'sun end' of the line outside, but the actual laser inside, am I going to lose a bunch of pump power in the lines? And where can I get some decent fiber optic line? Thanks again  

Click to expand...

You could use a standard type fiber coupler. They generally have some kind of focusing lens that targets the end of the fiber. Use a large convex or fresnel to focus onto the coupler. You would need one for each fiber. With good focusing you could get as high as 70% efficiency maybe even more with the larger multimode fiber.

I haven't done the calculations but you might want to figure out if something like 2.5W/m^2 * Efficiency % * fiber count is enough pump energy. YAG is about the easiest solid state gain media to get lasing so if anything will lase with sunlight, YAG will.[/quote]

Sounds good. Hopefully I can start building something in the next week or so. Any suggestions as to where to find the fiber/couplers at a decent price? is ebay my best bet?

It's an interesting experiment, but i foresee many problems with it.

As mentioned, sunlight is mostly not-808 nm, useless energy. You will need to filter that out very well, otherwise you will destroy the crystals well before any chance of lasing.

The other problem is that sunlight is continous. In pulsed operation with flashlamps, the instantanous power is enough for lasing, but the average power is low enough not to damage your lasing medium and cavity. I think it would require some contraption to pulse sunlight, such as a rotating disc with a hole in it... but that creates the problem of getting enough pulse power to make things work.

I'm just going to find a rod meant for CW

Also, when talking about the amount of 'usable' light in sunlight, I don't think I'll need to filter it as long as I'm using a robust CW rod. I mean, they normally pump the rods with flashlamps which I'm sure also project a lot of useless light. I think I'm going to build some sort of attenuator at the lenses which face the sun. This way (in theory) I can control the output power to a 'safe' level, should I need to.

Don't forget to get one of those telescope tracking motors so your collection rig will follow the sun across the sky. I picture in my mind what looks like the high gain antenna from the apollo space missions. The antenna mounted to the service module and contained four small parabolic reflectors. In my mind I see six or eight small parabolic reflectors each focusing the sunlight onto a fiber coupler feeding your pump chamber. This probably isn't very efficient but when I think about it that's what pops into my head. Actually a set of fresnel lenses would be easier to work with.

So when I get the light into the fiber, do I need to 'collimate' it, or can I just stick it directly under the focal point of the Fresnel lens? I guess it wont really matter since I'm not trying to get any sort of 'quality' light out of the other end. I guess I just answered my own question ;D

First things first... I need to find a place to get the fiber!

Hi this project sound very interesting! I'm not a scientist myself but i am in the process of setting up an open source project to create a 'sun cutter', basically a sun-pumped laser which sits on a mixture of the many open source designs for a x and y table which would be solar powered too. The aim is to create a machine that can be used in off-grid environments whether urban or rural. I am curious if any of you have succeeded with pumping a small standard laser with sunlight and if any of you would be interested in participating in this open source project. I am studying at the RCA in london on the MA design product course and i'm also trying to get scientific advise from the Imperial College London. But i really need collaborators, the more the better!!!